During a 2021 research cruise in the North Atlantic, scientists from the University of California, Santa Barbara examined the impact of four intense storms on the ocean’s ability to capture and store carbon. The study, published in the journal Global Biogeochemical Cycles, revealed that storms initially broke down organic particles called marine snow into smaller fragments, temporarily limiting carbon transport to the depths. However, two days after the storms subsided, instruments recorded pulses of falling particles, indicating a previously unknown mechanism by which the ocean captures carbon from the atmosphere. these are the first field observations illustrating the link between ocean turbulence and the processes of particle aggregation, disaggregation, and settling[1]
The team, led by oceanographer David Siegel, found that storms deepen the ocean’s mixed layer, pushing organic particles far below their usual depths. After the storms end, this layer becomes shallower again, allowing the fragmented particles to reaggregate into larger marine snow clusters that sink faster to the bottom. These are the first field observations illustrating the relationship between oceanic turbulence and the processes of particle aggregation, disaggregation, and settling.
The expedition also overturned previous assumptions about the consumption of marine snow. At depths between 200 and 500 meters, researchers observed that biological processes break down large particles at a rate of about 12 percent per day. Professor Alyson Santoro and PhD candidate Nicola Paul calculated that microorganisms consume less than half of the marine snow, with zooplankton playing the main role in its consumption. Previous models had attributed a dominant role to microorganisms, but new data indicate a significant contribution from animals living in the mid-ocean layers. The expedition also refuted assumptions regarding what consumes marine snow[2]
The ocean’s biological carbon pump transports about 15 percent of the 55 to 60 billion metric tons of carbon bound annually by phytoplankton from the water’s surface to depths where it can be sequestered for long periods. The study’s results help to better understand the variability of this process and explain scientists’ difficulties in creating precise forecasts of carbon fluxes in the oceans. The ocean’s biological carbon pump transports about 15 percent of 55 to 60 billion metric tons[3]
Co-author Uta Passow from Memorial University of Newfoundland emphasized that these new findings will help incorporate these processes into carbon cycle models used in climate simulations.
The 2021 expedition faced logistical challenges related to the COVID-19 pandemic. Its start was delayed by a year, and organizers coordinated activities across more than 40 institutions from five countries, ensuring safety aboard three research vessels with no infections reported. For this effort, the team received the NASA Administrator’s Group Achievement Award in 2022. Researchers from many countries will meet in Glasgow in March 2026 to develop an action plan.[5]